import {AudioMimeType, GetArrayBuffer, GetFileInfo, GetMetaCoverURL} from "./util"; import {BytesHasPrefix, SniffAudioExt} from "@/decrypt/utils.ts"; const musicMetadata = require("music-metadata-browser"); const MagicHeader = [ 0x79, 0x65, 0x65, 0x6C, 0x69, 0x6F, 0x6E, 0x2D, 0x6B, 0x75, 0x77, 0x6F, 0x2D, 0x74, 0x6D, 0x65, ] const PreDefinedKey = "MoOtOiTvINGwd2E6n0E1i7L5t2IoOoNk" export async function Decrypt(file, raw_filename, _) { const oriData = new Uint8Array(await GetArrayBuffer(file)); if (!BytesHasPrefix(oriData, MagicHeader)) return {status: false, message: "Not a valid kwm file!"} let fileKey = oriData.slice(0x18, 0x20) let mask = createMaskFromKey(fileKey) let audioData = oriData.slice(0x400); let lenAudioData = audioData.length; for (let cur = 0; cur < lenAudioData; ++cur) audioData[cur] ^= mask[cur % 0x20]; const ext = SniffAudioExt(audioData); const mime = AudioMimeType[ext]; let musicBlob = new Blob([audioData], {type: mime}); const musicMeta = await musicMetadata.parseBlob(musicBlob); const info = GetFileInfo(musicMeta.common.artist, musicMeta.common.title, raw_filename); const imgUrl = GetMetaCoverURL(musicMeta); return { status: true, title: info.title, artist: info.artist, ext: ext, album: musicMeta.common.album, picture: imgUrl, file: URL.createObjectURL(musicBlob), mime: mime } } function createMaskFromKey(keyBytes) { let keyView = new DataView(keyBytes.buffer) let keyStr = keyView.getBigUint64(0, true).toString() let keyStrTrim = trimKey(keyStr) let key = new Uint8Array(32) for (let i = 0; i < 32; i++) { key[i] = PreDefinedKey[i].charCodeAt() ^ keyStrTrim[i].charCodeAt() } return key } function trimKey(keyRaw) { let lenRaw = keyRaw.length; let out = keyRaw; if (lenRaw > 32) { out = keyRaw.slice(0, 32) } else if (lenRaw < 32) { out = keyRaw.padEnd(32, keyRaw) } return out }